Solid compound of nitric and sulfuric anhydrids and process of making same.



. W. SGHULTZE. V SOLID COMPOUND 0F NITRIC-AND SULFURIG AN HYDRIDS ANDPROCESS OF MAKING SAME. APPLICATION I'ILED MAY 5, 1908.

10475576. Patented De c.17, 1912.

WITNESSES: IIWEIVTUR awn? By A TTORNE Y8 of Maspeth, Long Island, in thecounty and.

Making Same, of which thefollowing is a chemicallycombined together.

- to completely hydrate at least one ofthe ture.

) absorbers A and -A, preferablymade of in at number of horizontalradial branches Nitric acid,vprefera,bly ofnot less than 94% strength, Iis simultaneously fed into A through the glasstube G which communi inthe drawing). The lower end of G may beslightly bent and preferablyreaches hebeen' supplied to thevt-rade-in liquidftorm,

ping out this invention.

- a, a clamped tothe main body by iron rims wInLIAi/i so ULrzE, on NEW'roan, N. "COMPANY, or NEW YORK; NLYA;

SOLID conrounn or NITRIC AND SULFUR "UNITED .jiS -AT QFFICE at,ASSI-GNOR TO GENE AL crisis/treat A- CORPORATION or NEW, YORK.

1o nnynn'ms Am) rnocnss or" MAKING- SAME. I

Specification at ,Application filed May 5, 1

To all whom Liana/y concern" 4 v -Be it. known that I, Winner-mtSCHULTZE. a citizen of the United States, and resldent born-ugh ofQueens, city, and State of New York, have. invented certain new anduseful 'Improx'ements in SolidCompounds of Nitric and, SulfuricAnhydrids and Processes. of

specification. s a a a This invention relates to asolid crystallinecompound containing sulfuric and nitric acids, or, more precisely, theiranhydrids,

Mixtures of-sulfuric'and nitric acids are largely, used, in certainmanufacturing proc- -esses,. for .-n1trat1ng=,? and have; hitherto andmore or. less diluted state-,4. a, contain? ing water in proportion morethan sufficient two acid-anhydrids contained in the mix- A solid mixedacid compound, such as may be'prepared according to this invenomyincostoft-ransport, convenience in Th'e accompanying drawing is a sectionalelevation of an apparatussu table,for carry- This apparatus consists oftwo cylindrical" lead, and closed at' -the -top by leadcovers b,5,screw:bolts 0,0, and nuts d, d.

Sulfur t'riox'id gas or vapor, or a suitable gaseous mixture containing:the same (such as is obtained for instance by the contact process) isintroduced through the lead pipe B, which terminates near the bottom ofA cates at the top with a reservoir '(not shown low the orifices throughwhich the S0 is discharged from the branches e. The ab steam and water.

Letterslatent.

908. Serial No. 430,914.

drawing intermittently or continuously a portion of the contents of A. Fis a steamacket, with steam inlet i, and outlet 0 for same sufli'cientlyhigh to prevent solidification of thebath therein, while at the same It.surrounds the lower Patented Dec. 17, 191 2.

time preventing it from rising toi the point i at which the productdecomposes with liberation of nitrous fumes. Much of the heat requiredto maintain the'proper temperature isfurnished directly by the reactionand'absorption, itself.

Tis athermoineter for observing the temperature in A. A convenienttemperature to maintain is about that of open steam, 100 'deg; C. Othermeans may be substituted v for the steam-j acket F.

. From A the unabsorbed and uncondensed gases or vapors pass out througha lead pipe G into a sight bottle S, and thence through another lead ipeH, with vertical limb B and distributing branches 6'', similar to thebranches e inA. :These distributing branches e are immersed in sulfuricacid, preferably of 97-98% strength, which servestoarrest and recoverpractically all the vapors of SO; and I-INO which escape absorption'inA; The acid in A requires 06- casional renewal, A tap K is provided forwithdrawing this acid when desired. From A the residual gases passthrough pipe L to a second sight bottle S",.c'ontaining a layer of Waterat the bottom, and thenc'e'to 'the pump or other device-employed to"draw the gases through theap-paratus.

To operate the apparatus described, the absorberA is first of allcharged with a mixture 'ofab'out 300 parts fuming sulfuric acidcontaining about free SO,- and about parts of nitric acid containingabout 96% HNO Q The second absorber is charged with sulfuric acid ofabout 98% strengthQA current of sulfur trioxidgas or vapor, or gases orvapors containing the same, is then aspiratedthrough the appar ratns,entering the-same at the inlet of B and bubbling through the mixedacids.The residual gases pass off to the ump or other draft producing device(not 5 own in draw ing) at 0. At the same time a regulated stream ofnitric acid is fed in through C. The streams ofSO and HNO, are regulatedin accordance with the appearance of the 6 sight bottles S and S, inwhich there should be at the most only a slight mist. The stream of HNO'may also be regulated in proportion to the S passed through, that istosay in accordance with the proportion in which these-two ingredientsoccur in the product. The temperature in A is kept at about 100 deg. Cby the aid of the steam bath F. The product is withdrawn continuously orintermittently through discharge pipe D and cook E, and is allowed tocrystallize. It may, if desired, be purified by remelting,re-crystallizing and drainingv off the mother liquor preferably. by.suction, care being taken to exclude moisture from the apparatusthroughout such operations.

The invention may be carried out in various other ways. Thus, instead ofbubbling SO through a liquid bath of mixed sulfuric and nitric acids,such a mixture maybe caused to flow down a tower'through which at thesame time sulfur trioxid is passed. Again, the composition ofthe liquidin the ,absorber may be varied. It may, at the commencement. of theoperation consist only of nitric acid, which is at first graduallysaturated with sulfur trioxid (without feeding in any further quantityof nitric acid), until it has acquired a suitable composition, such asthat of the product to be withdrawn, after 5 which sulfur trioxid andnitric acid are fed simultaneously, as in the example-quoted in fullabove. A similar treatment can evidently be applied to mixtures ofsulfuric and nitric acids which contain relatively too 40 high apercentage of nitric acid or of water.

In the last case it may be necessary to add, not only sulfur trioxid,but also concentrated nitric acid. The absorbing liquid may also forexample consist of mother liquor from a previous operation (6. g. if theproduct isv recrystallized) or of a melted down portion got a previousbatch of crystals. If the composition of the absorbing acid departsconsiderably from that of the crystallized product, the liquid drawnfrom the absorberwill not set completely. solid, but will separate intocryst-alsand mother liquor. The crystals may be freed from mother liquorby any of the known methods (draining, cent-rifugal action) carefullyexcluding moisture, and the mother liquor may be returned to theabsorber. a Another manner of carrying out this invention consists inconducting vapor of sulifuric'anhydrid and nitric acid, conveyed,

say, in a current of warm dry air,-into a suit,-

able chamber, vin which combination takes pliisce with' form'ation ofthe mixed-acid crysa v Lastly may quoted an examplein which ing sulfuricacid or ,oleum.

time decomposed.

the sulfuric anhydrid is presented, not in the form of vapor, but in theform of fumgrams of nitric acid containing about 96% -HNO were graduallyadded, cooling occasionally, 1255 grams of oleum containing 68% freesulfuric anhydrid. Crystallization started before the mixture hadassumed room-temperature. After 48 hours standing the crystals wereseparated as far as possible from the mother liquor on a suction filtersup lied with air dried over sulfuric acid. Tile total weight ofcrystals obtained was about 1060 grams, or 67% of the initial material,that of the mother liquor, 322 grams or 33%.

Other proportions of nitric acid and oleum may be used instead of thoseindicated above, although not all proportions are equally favorable toobtaining a ood yield. In my. investigations I have ound that crystalsof the composition corresponding to the formula N,O (SO,),HO can beobtained from mixtures of nitric acid and oleum containing from 12% to27% of concentrated nitric acid. I

Theproper'ties of the crystallized product prepared by any of the abovemethods are as follows: The crude crystals are of irregular shapeasarule; sometimes they form rectangular plates, more orless welldefined, according to the rate of their formation. Their color variesfrom yellow 'to white.

Their specific gravity is about 2.18. Their point varies ,.according totheir demeltin purity, say from 93 to lOt deg. C.

gree 0 When heated to 170 deg. C. they undergo partial decomposition,with eflervescence.

A sample, kept for about two minutes at this temperature, was found 'onanalysis to have increased by 02% in N203 content. Another sample wasfurther heated for about 15 minutes, until the temperature reached 214dg. C, when titration with potassium permanganate showed that about 25%of the nitric acid present had by this The crystals are stronglyhygroscopic. Their vapor pressure is small, consequently they do notfume appreciably when exposed to the air at ordinary temperature,andwhen kept in rubber-stoppered bottles for months, hardly attack therubber. The practical advantages resulting from this low vapor tensionand high melting point are obvious, since the former limits to points atwhich there is actual contact any corrosive action which the mixed acidcrystals might have upon thev containers used in storage and transport;while the latter insures that the material retains its solid form underall ordinary conditions of storage and transort. p The composition ofsome of the crystals obtained is shown in the subjoined tabulatedresults o-fanalyses, togetherwith which are quoted, for comparison, thecorresponding figures calculated'for a compound of a composit-ioncorresponding to the empirical formula HO NS This, forcorivenience maybe written: N,O 0S ,H O.

Table .1 shows the results of analysisdirectly, expressed as usual interms of per-.

being determined centages, the water difference.

Table'II shows the percentages ofthe es-' sential constituents,calculated on the weight .of the product diminished by the weight of theaccidental impurities, viz., N 0,, and

Table III shows the ratio of the amount ofeach of the normalconstituents, (as stated in Table II) to the amounts theoreticallycorresponding to the formula N 0 S0 ,,.H;,O.-

Tame I. v

Crystals, twice recrystallized, sample B.

Crude crystals. j

Calculated for Sample A. Sample B.

TABLE II.

Crude crystals. Crystals, twice recrystallized, sample B.

I Sample A.

Sample B.

8 ass s sass 1 said TABLE III.

' Crude crystals. Crystals, twice recrystallized, sample B.

Sample A. Sample Sample A was prepared with the lead represent typicalit must be clearly mula N30}, (80,) .H O, as indicated above.

a I am aware t-hata compound of a somewhatsimilar composition-has beendisclosed hyNVeber Pogg. Amt. 1871, w 142, 'p. 602); \Vebefls' compoundcontained more water than the product'described above, namely an amountcorresponding to the formula N O QSO ,,.3H. hadno definite meltingpoint, but decomposed when heated,-with liberation of brown fumes' (seePogg. Ann. 1871, r. 142,100 0515.), and has neverbeen' of commercialutility, .nor could it have been. This compound fWebers is thereforeonly a laboratory'curiosity without any practical utility, and Itherefore do not claim herein suchproduct or any process which yieldssuch product.

Having thus described my invention, I

' claim:

1. As a'n' article of manufacture, a solid composition containingsulfuric and nitric anhydrids and water in quantity less than.

that corresponding to three molecular proportions for every molecularproportion of the compound, whioh -has the following properties, viz:that said compounds at ordinary temperaturesform a water clear,

white or yellowish, hygroscopic crystalline mass, sometimes displayingwell-defined rec tangular plates, which has a specific gravity of. about2.18, melts at 93-104 degrees 0., and on further heating decomposes withevolution of nitrous fumes.

2. As an article of manufacture, the hereinbefore described compound ofsulfuric anhydrid, nitric anhydrid and water 'in the proportionscorresponding to the formula N O (SO ;H O, characterized by thefollowing properties, viz., that said compound at ordinary temperaturesforms a waterclear, white or yellowish, hygroscopic crystalline mass,sometimes displaying well defined rectangular plates, which has aspecific gravity of about 2.18, melts at-93-104 deg.- (3., and onfurther heating decomposes with evolution of nitrous fumes.

3. The herein described process which consists in adding sulfuricanhydrid to concentrated nitric acid until a solution is formed fromwhich crystals can be deposited upon cooling and then cooling suchsolution until crystals are deposited.

4. The herein described process which consists in absorbing sulfurtrioxid vapor in a bath containlng' concentrated n1tr1c acid until asolution is formed from which crystals can be deposited upon cooling andthen cooling such solution until crystals are deposited' H 5. The hereindescribed process which consists in adding sulfuricanhydrid to a mixtureof concentrated nitric acid and con-' centrated sulfuric acid until asolution is formed from which crystals can be depositcd upon cooling andthen cooling such so- I lution until crystals are deposited.

6. The process which consists in absorbin sulfur trioxid vapor in aliquid consisting of concentrated nitric acid and fuming sulfuric acidin about that proportion which makes the ratio of the contained N 0 tothe Z total contained SO as N O :4SO said liquid being maintained at atemperature above about 100 deg. C., at the same time v introducing astream of concentrated nitric acid, regulating the rate of introductionof this stream so that the quantities of SO, and f of N 0 admitted perunit of time are about in the proportion indicated by the formula 15 3 030 said regulation being effected in accordance with the indicationspresented by the appearance of the residual gases, withdrawing a portionof the absorbing liquid, allowing the same to cool with dcpo-' sition ofa solid, and collecting said solid product.

In testimony whereof I have hereunto set' my hand this 1st day of May,1908 VILLIAM SCHULTZE.

Witnesses:

JOHN LoTKA, J OHN A. I{EI-ILENBECK.

Copies of this patent may be obtained for five cents eaeh,,by addressingthe "Commissioner of Patents.

Washington, I). C.

